Réponse :
Bonjour,
[tex]A = (4x + 5)(x + 3)\\\\= 4x \times x + 4x \times 3 + 5 \times x + 5 \times 3\\\\= 4x^2 + 12x + 5x + 15\\\\= 4x^2 + 17x + 15[/tex]
Vérification:
[tex]Pour \ x = 2\\\\A = (4 \times 2 + 5) \times (2 + 3)\\\\= (8 + 5) \times (2 + 3)\\\\= 13 \times 5\\\\= 65\\\\\\\\A = 4 \times 2^2 + 17 \times 2 + 15\\\\= 4 \times 4 + 17 \times 2 + 15\\\\= 16 + 34 + 15\\\\= 65[/tex]
